Mr. Monk and the Sleeping Suspect - S2-E7
Plot hole: Technically, Brian Babbage's plan would never have worked due to the fact that all outbound mail goes to a main post office from the local post office and then placed through scanners to determine the contents, which would have inevitably exposed the bomb inside.
Mr. Monk and the 12th Man - S2-E9
Plot hole: Monk identifies the killer because of a shirt sleeve that gets ripped off... he noticed the button is sewed on in a unique manner with the threads parallel as opposed to the "standardized" crisscross pattern. The killer and Monk coincidentally use the same dry cleaner and Mrs. Ling sews buttons parallel because it's her style. Dialogue in the episode indicated she is the only one who sews buttons on like that. But I checked over 20 button up shirts here at my house and the ratio of crisscross to parallel button sewing methods is 50% of each - hardly some unique identification method.
Mr. Monk and the T.V. Star - S2-E12
Plot hole: Unless I missed something, the killer didn't wipe his prints off the knife he used to kill his ex-wife.
Mr. Monk Goes to Jail - S2-E16
Plot hole: It is unrealistic that a prison cook who did not punch out would not be missed or found until the next day, especially after a lock-down scenario as portrayed in this episode, where a meal has been poisoned - likely in that very kitchen.
